1. Field of the Invention
The present invention relates to an auxiliary device for barge construction, in particular, an automatic reversing-reposition rocker arm for sliding a large jacket from launch barge into the water. The auxiliary device is usually used in the marine oil engineering field.
2. Description of Related Art
The launch barge is different from other barges, two rocker arms with pivoting shaft are provided on the barge stern, and the rocker arm is a steel arm for supporting the jacket to rock together just after the jacket sliding into the water.
As shown in FIG. 1, the existing rocker arm includes a rocker arm body 1, and the rocker arm body 1 is formed by welding an outer plate and some crossed inner partitions to make a steel box beam. On the center of the bottom of the rocker arm, a rocker arm pivoting shaft 3 is attached by welding, and the revolving point of the pivoting shaft 3 is on the after-perpendicular line.
When using, a pair of rocker arms are attached in the groove of the barge stern, and the distance of both rocker arms are in accordance with the engineering requirement of the skid beams spacing, the rocker arm pivoting shafts are fastened to the groove of the barge stern by a locking device, so as to make the rocker arm pivoting about the shaft. Half of the rocker arm extends beyond the stern. The head of the rocker arm connects with two longitudinal skid beams of the main deck which cross through the barge. The rocker arm and the skid beams can be adjusted near the middle of the barge to meet the different sizes of jacket launching. At the last stage of the jacket launching, the whole weight of the jacket applies to the rocker arm, and the jacket is launched by the reversal of the rocker arm.
After rocker arm is reversed following the launching of the jacket, usually, the external force acting on the rocker arm and the self weight of the rocker arm is not enough to make the rocker arm to automatically reverse and reposition, and its reversal and reposition is made by means of external force and manual operation. It not only wastes the construction cost, but also increases the risk of offshore engineering. Owing to the larger moment of inertia of the rocker arm about the pivot shaft, the reposition by means of the external force is hard to control the angular velocity of the rocker arm, thus, it is easy that the deck is damaged to some extent by the impact force of reposition.